Gravity analysis to estimate the mud stream direction in porong by applying the delaunay approach

Lumpur Lapindo eruption at Porong, Sidoarjo is still continuing, it is suspected triggered by the flow of high-pressure mud. Measurements were performed for analyzing the subsurface structure where there was subsidence of soil and mudflow in the affected areas of Lumpur Lapindo with gravity method. The results of gravity data measurements are not always regular according to planning due to unpredictable field conditions. Therefore in this research writer used geostatistics method in interpolation of gravity anomaly data. Second Vertical Derivative (SVD) is a method used to determine the fault structure. The gravity anomaly value in the Porong area is 8 mgal to -32 mgal. High-value gravity anomalies in the northwest region with the highest anomaly value of 8 mgal indicates an increased of mass density and soil degradation. While the gravity anomaly of low value in the northeastern region with the lowest anomaly is -34 mgal which indicates a decrease in subsurface mass density. The fracture structure that has been obtained can be used to determine the direction of Sidoarjo mud movement.